<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>then返回的也是promise对象</title>
</head>
<body>
<script>
  let p = new Promise((resolve, reject) => {
    resolve('数据')
  })
  
  let t1 = p.then(data=>{
    return '123'
  },reason => {})


  // p.then(data=>{},reason => {}).then(data=>{},reason => {})

  console.log(t1)
</script>
</body>
</html>